The influence of ratio of 3, 4-bisnitrofurazanfuroxan(DNTF) to RDX on dynamic mechanical properties for modified double-based propellants(DNTF/RDX-CMDB,DFR) was studied by dynamic mechanical analyzer(DMA). The characteristic values of dynamic mechanical properties at multi-frequency for DFR series propellants were obtained. Results show that the ratio of DNTF to RDX content can obviously affect the dynamic mechanical properties of DFR propellants. Two β-relaxations(signed β₁ and β₂ respectively),besides α-relaxation,appear on DMA curves of DFR propellants,and one of them(β₁-relaxation) is due to the effect of DNTF,that′s to say,the plasticization of DNTF to NC molecular can not be affected by adding RDX. The whole β-relaxations peak values(∑tanδ) for CMDB,both the DNTF and RDX added,is bigger than that only RDX added,hence,the plastic or toughness has been improved while the ability to resist external forces increased at low temperature. The DFR propellant that mass ratio of DNTF to RDX is 10：40 has optimal plastic or toughness at low temperature.